Olive is among the popular fruits and of a high economic value. Cleaning and grading of fruits may be considered important post harvest activities that improve fruit quality. This research aimed to develop a grading unit for better marketing. The measurements include some physical and mechanical properties of olive fruits that may be used in developing the proposed grading machine. The developed machine performance was tested and evaluated under different operational factors. The effect of screen slope angles, kinematic factor (ω2 r/g), screen mesh shape (circle cells, trapezoidal bars cells and round bars cells), specific feed rate, and spiral to screen speed ratio on grading efficiency, fruits clogging, grading capacity, energy requirements, and fruit damage were studied. Results showed that this machine is quite successful for grading olive fruits. The optimal operational conditions were 2.0 kinematic factor, 0.08 kg/m2 s feed rate, zero degree screen slope, 1.5 spiral to screen speed ratio and using trapezoidal bars cells. At these levels, the maximum grading efficiency of 95.4% was obtained with machine grading capacity of 450 kg/h, the minimum value of energy requirements of 5.8 kW.h/Mg and fruits clogging percentage of 0.58 %. The minimum fruits mechanical damage of 1.3 % was obtained. Results indicated that the grading machine could work properly, and the classification of olive could be done based on the fruit size. This machine has the potential to size other crops like potatoes, tomatoes, apples and citrus fruits.